Braking systems using electro-mechanical actuators (EMAs) have been considered as alternatives to conventional hydraulic braking arrangements. In one previously disclosed aircraft braking arrangement using EMAs, a plurality of EMAs are mounted on a brake carrier housing in an annular pattern about the axis of wheel rotation. The brake carrier housing is fixed to a torque tube having stator disks of a brake disk stack attached thereto. Rotor disks of the brake disk stack, which project between the stator disks attached to the torque tube so that rotor and stator disks alternate, are fixed to and rotatable with the wheel that rotates about an axis. The EMAs are selectively energized in response to a braking command, causing a motor-driven, reciprocating actuator piston (“ram”) to extend and engage a pressure plate positioned on one end of the brake disk stack to compress the brake disk stack and retard wheel rotation. One EMA-based braking system is disclosed U.S. Pat. No. 6,530,625, titled “Electrically Actuated Brake with Vibration Damping,” the entire contents of which are herein incorporated by reference.
Another EMA-based braking system is disclosed in U.S. Pat. No. 6,003,640, titled “Electronic Braking System with Brake Wear Measurement and Running Clearing Adjustment,” the entire contents of which are herein incorporated by reference. This patent discloses an alternative to visual inspection of wear pin indicators to measure wear of the brake disk stack and set running clearance. In this patent, position sensors are used to determine actuator ram position and set running clearance values. The inventor of this application has found, however, that the use of a dedicated position sensor in an EMA arrangement has certain drawbacks, such as increased cost, weight, and size. Use of a separate element for position sensing also reduces the reliability of the system. An embodiment of the present invention addresses these drawbacks as well as other drawbacks of known EMA-based braking systems.